This invention relates to apparatus and methods used in analyzing constituent components in a fluid such as blood serum. Such apparatus and methods typically involve the application of a reagent to a sample of blood serum in a transparent laboratory vessel known as a cuvette. The reagent conventionally binds to a predetermined constituent component of the blood serum samples, thereby isolating that component for analysis by whatever means may be employed.
The blood serum sample as well as the different reagents that may be used for analysis purposes are initially placed in a suitable container. Probes are then ordinarily used to aspirate small quantities of the reagent and the blood serum sample respectively, and deposit them in the cuvette for analysis in a well-known manner. The probes are conventionally manipulated by mechanical arms such as disclosed in U.S. Pat. No. 4,326,851--Bellows, which are, in turn, under the control of microprocessor electronics. Though this technique has been successful, it is not without certain drawbacks and deficiencies which render such apparatus and methods prone to error on some occasions. More particularly, the probes used for transferring reagent and blood serum sample fluids are subject to cross-contamination and other problems which may adversely affect the results of the analysis.
For example, different reagents are, of course, used to isolate different constituent components of the blood serum sample to be analyzed. When the probe used to deposit one reagent in the cuvette is subsequently used to transfer a different reagent, residue from the first reagent often mixes with the subsequent reagent thereby contaminating the latter. Similarly, when the probe used to transfer one sample of blood serum is subsequently used to transfer a different blood serum sample, the latter sample may become contaminated with residue from the former. In either situation, the cross-contamination may result in an erroneous analysis of the sample of blood serum then being tested.
It is, therefore, a primary object of this invention to provide improvements in apparatus and methods useful in the analysis of fluid samples such as blood serum. These improvements are particularly useful in sensing the fluid level in such apparatus, permitting smaller sample volumes to be employed. It is another object of this invention to provide improved apparatus and methods for analyzing such fluids wherein the likelihood of cross-contamination is minimized, and the accuracy of the analysis is enhanced. Other objects of the invention will become apparent upon reading the detailed description of the preferred embodiment of the invention summarized below.